Automatic coin-accepting machines. in addition to incorporating a coin validator to check the trueness of the coins inserted, mostly have a money changer which reimburses the balance exceeding the price of the desired article or service in small change. For this purpose, the money changer has coin reservoirs from which the small change is reimbursed. The most frequent type of the coin reservoirs are so-called coin tubes in which the coins are stacked like in a column. Such known money changers have three or four coin tubes for the small change coins.
Although it is possible to monitor the filling level of the coin tubes by watching the insertion and delivery of coins the real number of coins in the coin tubes frequently does not agree with the number counted. Therefore, it is also known to arrange filling level sensors at the upper and lower ends of the coin tubes that emit a signal if the column of coins goes beyond an upper amount or falls below a lower amount. When the tube is full the coins will be routed directly into a cash-box. When the filling level falls below a predetermined lower degree the acceptance of coins is blocked or the customer is signaled that it is impossible to return small change.
Various sensors have become known to determine the filling level of coin tubes. A so-called light barrier is frequently used which has a light-emitting element and a light-sensitive receiving element. U.S. Pat. No. 4,413,718 has made it known to superpose the two elements on one side of a coin tube and to dispose a prism on the opposite side of a coin tube to reflect the light bean back to the receiving element. The advantage of such an arrangement is that the lines can be fed to the elements on the same side of the coin tube. Nevertheless, there is the disadvantage of the great expenditure in assembling the money changer with the coin tubes and the associated light barriers. Such expenditure will naturally increase with the number of light barriers. For example, a measurement of the filling level can be desired to be made between the ends of a coin tube. It would be necessary to provide three light barriers per coin tube in such case.
It is the object of the invention to provide a money changer for automatic coin machines, which is particularly easy to manufacture and assemble and involves minimal manufacturing expenditure, the accuracy of the light barriers being sufficient to measure the filling level in the coin tubes.